This invention relates to newly identified polynucleotides, polypeptides encoded by them and to the use of such polynucleotides and polypeptides, and to their production. More particularly, the polynucleotides and polypeptides of the present invention relate to the sodium dependent phosphate transporters family, hereinafter referred to as IPT-1. The invention also relates to inhibiting or activating the action of such polynucleotides and polypeptides.
Phosphate retention has been shown to play a critical role in the development of uremic bone disease. Blockade of intestinal absorption of phosphate could provide an important target for prevention of uremic bone disease in patients who have end stage renal disease (ESRD) and possibly a target for slowing the progression of renal disease itself. Patients with ESRD cannot excrete phosphate, and they develop hyperphosphatemia, secondary hyperparathyroidism and uremic bone disease. Current treatment of these patients involves dietary phosphate restriction and phosphate binders, both of which have severe drawbacks. Blockade of phosphate absorption with a specific inhibitor of the intestial phosphate transporter would provide a major advance in the treatment of these patients. This indicates that the sodium dependent phosphate transporters family has an established, proven history as therapeutic targets. Clearly there is a need for identification and characterization of further members of the sodium dependent phosphate transporters family which can play a role in preventing, ameliorating or correcting dysfunctions or diseases, including, but not limited to, chronic renal failure, end stage renal disease, uremic bone disease, and cancer.
In one aspect, the invention relates to IPT-1 polypeptides and recombinant materials and methods for their production. Another aspect of the invention relates to methods for using such IPT-1 polypeptides and polynucleotides. Such uses include the treatment of chronic renal failure, end stage renal disease, uremic bone disease, and cancer, among others. In still another aspect, the invention relates to methods to identify agonists and antagonists using the materials provided by the invention, and treating conditions associated with IPT-1 imbalance with the identified compounds. Yet another aspect of the invention relates to diagnostic assays for detecting diseases associated with inappropriate IPT-1 activity or levels.